Updated

The general who will now oversee the wars in Afghanistan and Iraq is vowing "unrelenting engagement" with allies in the Mideast and Central Asia.

Marine Corps Gen. James Mattis has officially assumed control of U.S. Central Command. He succeeds Gen. David Petraeus (peh-TRAY'-uhs), who left the plum post to take command of the Afghanistan war following the ouster of Gen. Stanley McChrystal.

In a ceremony at Central Command's Florida headquarters, Defense Secretary Robert Gates praised Mattis as a counterinsurgency expert who put off retirement after a nearly 40-year career to take the new job.

Mattis helped lead the Iraq invasion and most recently headed Joint Forces Command, which Gates plans to eliminate.